Question

The pair of Lanthanoid ions which are diamagnetic is

• A. Ce4+ and Yb2+
• B. Ce3+ and Eu2+
• C. Gd3+ and Eu3+
• D. Pm3+ and Sm3+

Answer 1

Answer: (A)

Ce4+ and Yb2+

Answer 2

1. Diamagnetic ions have no unpaired electrons.

2. $Ce^{4+}$ ([Xe]) has no unpaired electrons.

3. $Yb^{2+}$ ([Xe]$4f^{14}$) has fully paired 4$f$-orbitals.